1. Field of the Invention
The present invention relates to a sheet post-processing apparatus that holds sheets with images formed thereon ejected from an image formation apparatus such as a copy machine, printer and facsimile to perform binding processing, and to the image formation apparatus provided with the sheet post-processing apparatus.
2. Description of Related Art
In recent years, in image formation apparatuses that form an image on a sheet to eject, reduction in size of the image formation apparatus and increases in speed of image formation processing has proceeded, in order to respond to the needs of effectively using the space in an office and increasing the efficiency of work.
With such improvements in performance of the image formation apparatus, attachment apparatuses that receive sheets ejected from the image formation apparatus are also required to be reduced in size and have the function of sorting ejected sheets in good appearance.
For example, as a method of sorting sheets ejected from the image formation apparatus in good appearance, known in conventional attachment apparatuses is an apparatus capable of performing binding processing on sheets for each group ejected from an image formation apparatus, and sorting for each bundle without collapse of the bundle even after being delivered (For example, see Japanese Patent No. 3026221).
However, the above-mentioned conventional attachment apparatus has defects as described below. In other words, when the binding processing is performed on a corner portion of ejected sheets, the need arises of changing the position to bind depending on whether the sheets are ejected in phase-down (odd-number pages are ejected downward) or in phase-out (odd-number pages are ejected upward). However, in the conventional attachment apparatus, with the sheets fixed to a predetermined position, a stapler as binding means is moved to perform the binding processing on different corner portions of the sheets.
FIG. 10 is a schematic view showing the case where a stapler performs the binding processing in the conventional attachment apparatus. When performing the binding processing on different corner portions of fed sheets S, the stapler ST travels in the direction (directions showed by the arrows B and C in FIG. 10) perpendicular to the feeding direction of the sheets S shown by the arrow A in FIG. 10. However, the stapler ST has a predetermined width as shown in FIG. 10, and when performing the binding processing at positions in different corner portions of the sheets S, part of the stapler ST lies off the end portion of the sheets S. Therefore, it is necessary to reserve a width (shown by “L” in FIG. 10) corresponding to a travel range of the stapler ST, and a problem arises that the attachment apparatus cannot be reduced in size.
In view of the conventional defects, it is an object of the present invention to provide a sheet post-processing apparatus capable of performing binding processing appropriately on ejected sheets while implementing reduction in size of the apparatus and an image formation apparatus provided with the sheet post-processing apparatus.